This is legit the scariest thing I've seen you build, only for the forces involved and how close your fingers were to the mass wheel. Super informative!
thankfully these were solid brake discs, dangerous but not likely to fragment on falling and being unventilated they really have no protrusions to speak of
Stay safe, James. Those flywheels have a lot of energy in them and if that rocked off the table and hit the floor your plastic joints are going to give way and those flywheels are dumping all their energy into getting the heck out of there. Don't be in the way when they do.
I must second this. James, invest in or manufacture yourself a substantial safety shield before you do further experimentation with this. Those flywheels will not stop if they hit you.
Every machine should have an e-stop too. It seems he is just driving the motors directly from the receiver output so to stop the motors he needs to turn the knob down. It should be done like drones with an arming switch so the propellers won’t switch on without the switch turned on and will switch off as soon as the switch is turned off, preferably with braking.
You should print sheaths, or at least covers to the rotating disks. As is, you're one balance mishap away from losing fingers, especially since every time it falls, you reach for it with bare hands...
@@Shit_I_Missed. Gloves are a bad idea when working with rotating machines. The idea is that an abrasion is preferable compared to having the gloves being pulled in.
Lol don’t print them, get 1/4” thick clear polycarbonate sheet NOT ACRYLIC and thick metal corners then bolt it together. Only reason you probably don’t need thicker is those discs are smooth and solid metal incapable of fracturing under the rotational load applied.
A tether from the top of the unit to a strong fixed point above during testing will prevent dangerous devices like this tipping over. A mercury (for simplicity) tilt switch to cut power on toppling and automatic brake pads are also an idea. Explosive activated pads used on Sawstop table saws offers the best protection, but are expensive. Cheaper than sewing fingers back on though. ;)
It already has an IMU, the tilt detection could be done a lot better than using a mercury tilt switch. Perhaps the biggest error is that the flywheels seem to be directly controlled by that knob on the controller. It should at least be done like drones do it with a separate arming switch. In an emergency flicking a switch is much faster than turning a knob and it is also more definite, it is either on or off, there is no potential for it to be almost off.
eh the mounting holes aren't what take the load anyway they're there to hold the disc in place when there's no wheel, the way it's supposed to be constrained is by face contact alone, the wheel studs just happen to pass through it but shouldn't really be doing any force transmission
The video game one reminds me more of the reaction wheel demos with the cube that can 'jump' up to it's side then to a corner. I guess the ideal one would be three big reaction wheels for crude correction and three smaller gyros for fine control? But for now, I'm going to enjoy watching the somewhat scary device you have made. :)
You have quite a habit of making your contemporaries look like absolute posers. Thanks for the thousandth time for sharing your ideas. I really can't say how many times I've gotten invaluable design inspiration from your builds. Usually simple problems that I've overthought and overengineered you've solved with one part. Have to say, when the gyro frame fell over and the flange on the esc landed right on the battery I got flashbacks. It's always the pointy bits.
You can use reaction wheels as both a motive force and as a gyro (like you showed previously by balancing). Those little "dancing cube" robots do it where they use the wheels to fling themselves up then stand on end. Those usually have three wheels though, one for each axis. Maybe you could use some simple AI where it tweaks the PID values automatically to stabilize with various loads.
Brake rotors are a good proof of concept, but their weight is distributed more towards the hub than the edge. Concentrating weight on the outer radius will increase the moment of inertia on those flywheels allowing you to use smaller diameter flywheel or a lighter flywheel for the same angular momentum.
Cool - you've made something legitimately terrifying there - well done(I think?) for reaching out to catch it with no fear of the energy in those spinning brake discs. Beware the interaction of steel brake disc and ceramic/stone kitchen floor tiles though!
Scared the hell out of me when it fell over the first time. I really thought you were gonna grab the rotating gyro. Nice save. I've seen some footage from an old train that ran on a single track and balanced using gyros, in a time before microcontrollers. They used hydraulics coupled to the gyros to help compensate. It might be possible to do something similar with those pneumatic pistons that hold trunks or hoods open on cars.
@11:05 Bro put his hand on the thing and instantly realize and cut the speed! I say this shouldve been setup on the ground instead of a rickety table.. please be careful James
The threaded holes you bolted up to are for threading a bolt into to pop the rotor off of the wheel hub when removing it. That being their only function, they aren't as precisely placed as the lug holes or hub ring. So having used that as your mount point might be the source of your off center vibrations. Also a break shop should be able to balance your rotors for fairly cheap if you want to get better precision. Also using conical roller bearings rather than ball bearings would eliminate and play at the axle that may be contributing to vibration.
You could build a large sausage-shaped enclosure (punch-bag?) that is attached to the gyroscope inside by springs to resist and absorb impacts (like a washing machine)
Car disk brakes are a great source, but, even better van rear disk brakes. They're slightly heavier, but, because the mass is centered around the band (because of the parking brake), the weight is even better distributed for a gyroscope. Ultimately tho, i think the best gyro you could make, that's sized and weight properly is a 20" bicycle wheel that has a banding of lead wrapped around. This is what we used back in school and it was super easy to make. At that time, we took lead sheets (the stuff used for meeting the roof of a house with the brick work) and wrapped them into a long "snake", which then got mashed into the 20" rim, which in then locked it into place because of the lips that usually hold the tire in place. We also secured it with a banding of steel, which cleverly put the locking tab on the size with the least weight, which in turn got our wheel nearly perfectly balanced without much work. To turn it, we used to use a fan motor with a locking clutch from a lawn mower.
Your tightrope walking cheat device inspired me to build a toroid ring motor as a free-floating reaction wheel. Its not free floating, yet. But I think its got possibilities. As a satellite staibalizer maybe. no contact between the rotor and stator. And here the brake disks have alot of mass at low velocity near the centre, a toroid on spokes would make a much lighter machine with all the mass at one velocity. Love the channel, hope you have a holiday from this.
I love seeing the progression you make from small to potential giant three legged robot. Seems the past colabs with Colin Furze are influencing you a lot. 😊😅
I near had a heart attack when you dived for the moving unstable stabilizer. Would drum brakes work better for the gyro elements as they have a greater concentrated mass at the outer edge?
Given your base tripod, I would use ONE gyro, rotating in the horizontal plane with pitch/roll servos. Tipping it as appropriate, you should be able to use that single gyro to stabilize _both_ pitch and roll, without any unneeded yaw issues. You will also need to pay attention to the gyro position with an integral term, using the robot off-center moment to keep the gyro flat over the long term. But I believe that this would be considerably simpler than the monstrosity of multiple gyros and translation you appear to be planning. There is a basic problem at hand, namely that such a robot would be better controlled by leg force than position. That would support a controllable torque to precess the gyro to level when needed. But if you have _some_ spring constant built into the feet (rubber, or a sprung foot) you can use a small position offset to generate such a torque.
I love your brains brother....in strictly the most "bro-mantic" sense, of course. taking 2 things I absolutely LOVE ( TOTK & flywheels) and using them to make another thing I love (self balancing robots)....It's like you REALLY know your audience. never stop. ever.
Hi there James, cool video, looks terrifying. Just wanted to let you know your hair game is on point in this video. I'm a straight dude so I dunno what you changed, but it really works for you.
I wonder if two gyro wheels could be arranged lying down one above the other, like in the video but on its side, and each rotated on 2 axis synced together to balance for both pitch and roll at the same time.
I think you could make it self-righting pretty easily by just putting it on top of a hemispherical bottom (like on Weeble-Wobble toys) with a cylindrical extension at the top (so it could lie flat in the extremes)
Make a one wheel motorcycle (those with the driver inside the hollowed out wheel) which keeps its drivers on the lower end of the circle by a reaction wheel running inside the real wheel. This has the benefit of doing regenerative braking, too :)
I’m aware that it’s only being spun at low rpm’s but the printed flywheel with the ball bearings for added mass made me nervous! Although I’d like to see it spun at much higher speeds from a good distance! And behind something solid!
You'd probably need some quick servos, but it would be cool to have a robot balance like us lowly humans.. Have arms in various directions, and use them to shift the center of gravity. I don't know about you guys, but I can probably balance on one leg for 30 seconds. 😅
You've gotten terrifyingly close to your next project being a prosthetic hand! Please print some sheaths for the flywheel, training out the instinct to catch a falling project takes longer than adding safeties.
PID, D is to slew rate limit. its -ve , or should be . The PID is a beautiful thing. you can pimp it up with limits for parameters, anti-wind up, its always the integral thats the biggest trouble. Have fun.
have you experimented with old disk drives (HDD) as gyroscopes? The feeling of moving around a spinning HDD in your hand is rather weird. There are pretty fast, 7200 rpm are commun
Ever think you could make gyroscopic lift with a perpendicular forces to make a vortex that is couter to earths gravity. Like a spinning wheel that spins counnter to the way water spins in your toilet. Then have four wheels one fourth the mass of the big wheel spinning perpendicular to the big wheel?
Tip. Look into the linear motors from Washing machines. If possible use tubing attached to the body of the motors casing and spin that instead of car disks.
With a good instructor it could take as little as ten weeks to learn enough manual machining with a lathe and mill to make metal mechanisms strong enough to safely handle the forces shown in this video.
You mentioned that to get the an all axis balance you'd need 2 extra gyros totaling in 4. Would it not be possible to have 3 gyros set up in a triangle with independent rotation driven by motors instead of the sync gears? If it works it should save a lot of weight and reduce the footprint. Would also work really well with your tripod robot due to the small footprint on top
The idea of being struck by a spinning brake rotor seems ... unpleasant. You're dealing with amounts of mass that requires protection for bystanders in case things go awry.
Hello James. I think you make a mistake by having your PID-controller output a velocity and not a current/voltage/torque. By controlling the velocity, the resulting torque is not going to be what you expect.
The break rotors are not rated to spin that fast.. They are probably fine, but could easily fail catastrophically and kill you. Please put up some plexi/metal shielding or install some on the device. The design is otherwise really cool, as always!
I realize they are not as prevalent as before, but I think drum brakes may provide more mass in a similar volume of space. They may even all you to add more mass to the interior cavity of the brake drum. Also, as others have pointed out, I would make a shield or sheath around the rotating mass to protect yourself (and others) from injury. My nerves were on edge every time it started to fall and you reached out to catch it.
The mass moment gets a squared contribution from the distance to the axis of rotation. Putting all your weight on the perimeter is most weight efficient.
What about making giros rotating full 360 degrees? Giro blocks are quite compact and you can do this. And in this case you would not need to worry about limiting their angles.
03:36 Si vos hubieses "alivianado" el buje central de ese disco de freno, de seguro que hubieses obtenido una inercia mejor controlada y mejor aprovechada, con el consiguiente ahorro de peso en todo el prototipo. No todo es plástico en la vida, así como tampoco es modelar en 3D para luego imprimir. Saludos.
14:22 --- using a pivot point on the scooter deck to affix the unit may help in the unit righting itself and also a single linkage from the top of the unit to turn the handle bars like a person would if they were trying to balance on the spot- or would that be too hard for you to achieve James?
Ah, wheel rotors. one of my favorite attachment stabilizers. now if @Wintergatan just got a few rotors off a truck they'd save a lot of time reinventing the wheel.
Installing the belt drive on the other side of the discs would allow thecentre line of the disc to be on the centre line of the frame, i would just be Better.
11:04 I should just casually mention that reaching into openly spinning parts with lots of inertia like this can damage or rip your hand off. Even if this was a very human instinct/panic reaction you should not show it on youtube without a word of warning.
